dlsym: Make RTLD_NEXT prefer default version definition [BZ #14932]

When the first object providing foo defines both foo@v1 and foo@@v2,
dlsym(RTLD_NEXT, "foo") returns foo@v1 while dlsym(RTLD_DEFAULT, "foo")
returns foo@@v2.  The issue is that RTLD_DEFAULT uses the
DL_LOOKUP_RETURN_NEWEST flag while RTLD_NEXT doesn't.  Fix the RTLD_NEXT
branch to use DL_LOOKUP_RETURN_NEWEST.

Note: the new behavior matches FreeBSD rtld.  Future sanitizers will not
need to add versioned interceptors like https://reviews.llvm.org/D96348

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

1 files changed, 20 insertions, 0 deletions

diff --git a/elf/nextmod3.c b/elf/nextmod3.c
new file mode 100644
index 0000000000..cd7bdb36af
--- /dev/null
+++ b/elf/nextmod3.c
@@ -0,0 +1,20 @@
+int
+foo_v1 (int a)
+{
+  return 1;
+}
+asm (".symver foo_v1, foo@v1");
+
+int
+foo_v2 (int a)
+{
+  return 2;
+}
+asm (".symver foo_v2, foo@v2");
+
+int
+foo (int a)
+{
+  return 3;
+}
+asm (".symver foo, foo@@@v3");